Efficacy of Dual-Targeting Combined Anti-Tuberculosis Drug Delivery System in the Treatment of Tuberculous Meningitis

Interactions between CNS and immune cells in tuberculous meningitis

The central nervous system (CNS) harbors its own special immune system composed of microglia in the parenchyma, CNS-associated macrophages (CAMs), dendritic cells, monocytes, and the barrier systems within the brain. Recently, advances in the immune cells in the CNS provided new insights to understand the development of tuberculous meningitis (TBM), which is the predominant form of Mycobacterium tuberculosis (M.tb) infection in the CNS and accompanied with high mortality and disability. The development of the CNS requires the protection of immune cells, including macrophages and microglia, during embryogenesis to ensure the accurate development of the CNS and immune response following pathogenic invasion. In this review, we summarize the current understanding on the CNS immune cells during the initiation and development of the TBM. We also explore the interactions of immune cells with the CNS in TBM. In the future, the combination of modern techniques should be applied to explore the role of immune cells of CNS in TBM.

Macrophage-targeted nanoparticles mediate synergistic photodynamic therapy and immunotherapy of tuberculosis

Tuberculosis (TB) is an infectious disease caused by Mycobacterium tuberculosis (Mtb) that poses a serious global public health threat. Due to the high incidence of adverse reactions associated with conventional treatment regimens, there is an urgent need for better alternative therapies. CpG oligodeoxynucleotides (CpG ODNs) are synthetic oligodeoxyribonucleotide sequences. They can induce a Th1-type immune response by stimulating Toll-like receptors (TLRs) in mammalian immune cells, thus killing Mtb. However, due to the negative charge and easy degradation of CpG ODNs, it is necessary to deliver them into cells using nanomaterials. PCN-224 (hereinafter referred to as PCN), as a metal-organic framework based on zirconium ions and porphyrin ligands, not only has the advantage of high drug loading capacity, but also the porphyrin molecule in it is a type of photosensitizer, which allows these nanocomposites to play a role in photodynamic therapy (PDT) while delivering CpG ODNs. In addition, since Mtb mainly exists in macrophages, targeting anti-TB agents to macrophages is helpful to improve the anti-TB effect. Phosphatidylserine (PS) is a biological membrane phospholipid that is normally found on the inner side of cell membranes in, for example, plant and mammalian cells. When apoptosis occurs, PS can flip from the inner side of the cell membrane to the surface of the cell membrane, displaying a specific "eat-me" signal that can be recognized by specific receptors on macrophages. Therefore, we can use this macrophage-targeting property of PS to construct bio-inspired targeted drug delivery systems. In this study, we constructed PCN-CpG@PS nanocomposites. PCN-CpG@PS, combining PDT and immunotherapy, is designed to target macrophages at the site of a lesion and kill latent Mtb. We physically characterized the nanocomposites and validated their bactericidal ability in vitro and their ability to stimulate the immune system in vivo. The results demonstrated that the targeted nanocomposites have certain in vitro antituberculosis efficacy with good safety.

Polypharmacological Cell-Penetrating Peptides from Venomous Marine Animals Based on Immunomodulating, Antimicrobial, and Anticancer Properties

Complex pathological diseases, such as cancer, infection, and Alzheimer's, need to be targeted by multipronged curative. Various omics technologies, with a high rate of data generation, demand artificial intelligence to translate these data into druggable targets. In this study, 82 marine venomous animal species were retrieved, and 3505 cryptic cell-penetrating peptides (CPPs) were identified in their toxins. A total of 279 safe peptides were further analyzed for antimicrobial, anticancer, and immunomodulatory characteristics. Protease-resistant CPPs with endosomal-escape ability in Hydrophis hardwickii, nuclear-localizing peptides in Scorpaena plumieri, and mitochondrial-targeting peptides from Synanceia horrida were suitable for compartmental drug delivery. A broad-spectrum S. horrida-derived antimicrobial peptide with a high binding-affinity to bacterial membranes was an antigen-presenting cell (APC) stimulator that primes cytokine release and naïve T-cell maturation simultaneously. While antibiofilm and wound-healing peptides were detected in Synanceia verrucosa, APC epitopes as universal adjuvants for antiviral vaccination were in Pterois volitans and Conus monile. Conus pennaceus-derived anticancer peptides showed antiangiogenic and IL-2-inducing properties with moderate BBB-permeation and were defined to be a tumor-homing peptide (THP) with the ability to inhibit programmed death ligand-1 (PDL-1). Isoforms of RGD-containing peptides with innate antiangiogenic characteristics were in Conus tessulatus for tumor targeting. Inhibitors of neuropilin-1 in C. pennaceus are proposed for imaging probes or therapeutic delivery. A Conus betulinus cryptic peptide, with BBB-permeation, mitochondrial-targeting, and antioxidant capacity, was a stimulator of anti-inflammatory cytokines and non-inducer of proinflammation proposed for Alzheimer's. Conclusively, we have considered the dynamic interaction of cells, their microenvironment, and proportional-orchestrating-host- immune pathways by multi-target-directed CPPs resembling single-molecule polypharmacology. This strategy might fill the therapeutic gap in complex resistant disorders and increase the candidates' clinical-translation chance.

An effective nano drug delivery and combination therapy for the treatment of Tuberculosis

Drug resistance in tuberculosis is exacerbating the threat this disease is posing to human beings. Antibiotics that were once effective against the causative agent, Mycobacterium tuberculosis (Mtb), are now no longer usable against multi- and extensively drug-resistant strains of this pathogen. To address this issue, new drug combinations and novel methods for targeted drug delivery could be of considerable value. In addition, studies have shown that the use of the antidepressant drug fluoxetine, a serotonin reuptake inhibitor, can be useful in the treatment of infectious diseases, including bacterial infections. In this study, an isoniazid and fluoxetine-conjugated multi-walled carbon nanotube nanofluid were designed to increase drug delivery efficiency alongside eliminating drug resistance in vitro. The prepared nanofluid was tested against Mtb. Expression levels of inhA and katG mRNAs were detected by Real-time PCR. ELISA was applied to measure levels of cytokine secretion (TNF-α, and IL-6) from infected macrophages treated with the nano delivery system. The results showed that these nano-drug delivery systems are effective for fluoxetine at far lower doses than for free drugs. Fluoxetine also has an additive effect on the effect of isoniazid, and their concomitant use in the delivery system can have significant effects in treating infection of all clinical strains of Mtb. In addition, it was found that the expression of isoniazid resistance genes, including inhA, katG, and the secretion of cytokines TNFα and IL6 under the influence of this drug delivery system is well regulated. It was shown that the drug conjugation can improve the antibacterial activity of them in all strains and these two drugs have an additive effect on each other both in free and conjugated forms. This nano-drug delivery method combined with host targeted molecules could be a game-changer in the development of a new generation of antibiotics that have high therapeutic efficiencies, low side effects, and the potential to overcome the problem of drug resistance.